Disease relevance of rbcL

• The symbiont rbcL gene shared the highest degree of nucleotide sequence identity with the cyanobacterium Anabaena (69%) while the rbcS nucleotide sequence shared 61% identity with that of the green alga Chlamydomonas reinhardtii [1].
• Both the nucleotide +329 to +334 stabilizing sequence of rbcL and a transcription enhancing sequence that lies between +126 and +170 encode well conserved (cyanobacteria through angiosperms) amino acid sequences; the evolution of expression control elements within the protein coding sequence of rbcL is considered [2].

High impact information on rbcL

• The bacterial neomycin phosphotransferase structural gene fused to the maize chloroplast promoter for the large subunit gene of ribulose-1,5-biphosphate carboxylase (rbcL) has been integrated into the inverted repeat region of the Bam10 restriction fragment [3].
• RbcS suppressor mutations improve the thermal stability and CO2/O2 specificity of rbcL- mutant ribulose-1,5-bisphosphate carboxylase/oxygenase [4].
• The conclusions confirm and extend prior, more limited, studies on nuclear SSU and LSU rDNA genes and plastid-encoded rbcL and atpB [5].
• A chimeric reporter gene containing only the basic promoter is transcribed only 1-15% as actively as the endogenous rbcL gene, depending on the conditions under which cells are grown and tested [6].
• To delineate the rbcL gene promoter, chimeric reporter genes containing fragments of the 5' region of the rbcL gene fused to the coding sequence of the bacterial uidA gene, encoding beta-glucuronidase, were stably introduced into the chloroplast genome of Chlamydomonas by microprojectile bombardment [6].

Biological context of rbcL

• A phylogenetic tree based on rbcL nucleotide sequences nested two Chlamydomonas species as a "pyrenoid-regained" clade within a monophyletic Chloromonas "pyrenoid-lost" clade [7].
• We found that the proteins encoded by the rbcL genes had a much higher level of amino acid substitution in members of the Chloromonas lineage than they did in other algae [7].
• Thus, the 3' flanking regions of the rbcL and psaB genes can define the location of the 3' terminus of a transcript in vivo [8].
• Transformants harboring chimeric GUS genes fused to rbcL or psaB gene 3' inverted repeat sequences in their normal forward orientations accumulated GUS transcripts of a single size, whereas GUS transcripts of heterogenous sizes accumulated in transformants harboring the same gene lacking an inverted repeat sequence at its 3' end [8].
• We further demonstrate that expression from the GFPct cassette, under control of the rbcL 5'- and 3'-UTRs, is sufficiently robust to report differences in protein synthesis based on subtle changes in environmental conditions, showing the utility of the GFPct gene as a reporter of C. reinhardtii chloroplast gene expression [9].

Anatomical context of rbcL

• Analysis of chloroplast rbcL mRNA revealed that transcripts extending beyond the mature 3' end were not polysome associated [10].

Associations of rbcL with chemical compounds

• Photosynthesis-deficient mutants of the green alga Chlamydomonas reinhardtii were previously shown to arise from nonsense mutations within the chloroplast rbcL gene, which encodes the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39) [11].
• The chloroplast gene rbcL encodes the large subunit of ribulose bisphosphate carboxylase [6].
• We suggest that excess ROS mediate a decrease in the reduced/oxidized glutathione ratio that in turn signals the translational arrest of the rbcL transcript [12].
• It showed major similarities to the 18S rDNA of Dunaliella salina, with 95.3%, and to the rbcL sequence of Chlamydomonas tetragama, with 90.3% sequence homology [13].

Other interactions of rbcL

• We expressed a chloroplast luciferase gene, luxCt, in C. reinhardtii chloroplasts under the control of the ATPase alpha subunit (atpA) or psbA promoter and 5' untranslated regions (UTRs) and the rubisco large subunit (rbcL) 3' UTR [14].
• This result indicates that the coding region is necessary for sufficient expression of rbcL and psbA [15].
• An exogenous gene, placed between the 5'-upstream regions of the Chlamydomonas reinhardtii chloroplast genes, rbcL or psbA, and the 3'-end of the rbcL gene, do not have the same expression pattern as endogenous genes in the C. reinhardtii chloroplast [15].
• Transcripts of a chimeric rbcL-GUS construct in which the leader sequence of the rbcL gene was replaced by 103 bp of the leader sequence of the atpB gene were stable in illuminated cells [16].
• Likewise, interruption of psbB/T and psbH with a strong transcriptional terminator from the rbcL gene does not influence transcript accumulation [17].

Analytical, diagnostic and therapeutic context of rbcL

• Restriction-enzyme analysis and DNA sequencing showed that the amber mutation is still present in the rbcL gene of the revertant strain [11].
• Four genera of the Phacotaceae (Phacotus, Pteromonas, Wislouchiella, Dysmorphococcus), a family of loricated green algal flagellates within the Volvocales, were investigated by means of transmission electron microscopy and analysis of the nuclear encoded small-subunit ribosomal RNA (18S rRNA) genes and the plastid-encoded rbcL genes [13].
• Polypeptide products of the disrupted atpB and rbcL genes could not be detected using immunoblotting techniques [18].

References